POWER OF ATTORNEY

        Know all by these presents that the undersigned hereby constitutes and
appoints each of Malissa Daniels, Thomas Rosedale and Kathleen R. Henry, signing
singly, as the undersigned's true and lawful attorney-in-fact to:

        (1)	execute, for and on behalf of the undersigned, in the
                undersigned's capacity as a beneficial owner, joint actor, or
                similar capacity of securities which are registered under or
                subject to the laws, rules or regulations of any jurisdiction,
                any form, schedule, report, press release or other similar
                document as may be required by such jurisdiction's laws, rules
                or regulations, and any amendments thereto, in accordance with
                such jurisdiction's laws, rules or regulations, including
                without limitation Forms 3, 4 and 5 in accordance with Section
                16(a) of the Securities Exchange Act of 1934 (the "Exchange
                Act") and the rules thereunder, Schedule 13D or 13G in
                accordance with Section 13(d) of the Exchange Act and the rules
                thereunder and a Form ID, Uniform Application for Access Codes
                to File on Edgar;

        (2)	do and perform any and all acts for and on behalf of the
                undersigned which may be necessary or desirable to complete and
                execute any such form, schedule, report, press release or other
                similar document, and timely file such form, schedule, report,
                press release or other similar document with the appropriate
                governmental authority or regulatory body of the relevant
                jurisdiction and any stock exchange or similar authority; and

        (3)	take any other action of any type whatsoever in connection with
                the foregoing which, in the opinion of such attorney-in-fact,
                may be of benefit to, in the best interest of, or legally
                required by, the undersigned, it being understood that the
                documents executed by such attorney-in-fact on behalf of the
                undersigned pursuant to this Power of Attorney shall be in such
                form and shall contain such terms and conditions as such
                attorney-in-fact may approve in such attorney-in-fact's
                discretion.

        The undersigned hereby grants to each such attorney-in-fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the
rights and powers herein granted.  The undersigned acknowledges that the
foregoing attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming any of the undersigned's responsibilities to
comply with the securities laws, rules or regulations of any particular
jurisdiction.

        This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file forms, schedules, press releases or
similar documents with respect to the undersigned's holdings of and transactions
in securities which are registered under the laws, rules or regulations of any
jurisdiction, unless earlier revoked by the undersigned in a signed writing
delivered to the foregoing attorneys-in-fact.

        IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 19th day of October, 2021.

                                     SV7 IMPACT MEDICINE FUND LP

                                     By: SV7 (IMF) GP LLP, its General Partner


                                     By: /s/ James Costine
                                     Name: James Costine
                                     Title: Authorised Member